Programmatically create asp:Button and attach event in SharePoint

Question

I'm trying to create ASP.NET buttons programmatically inside an update panel in my SharePoint instance, but because of the page life cycle, I can not attach server side events on buttons.

Here is the code:

TableCell tcellbutton = new TableCell();
b.Click += new EventHandler(b_Click);
b.CausesValidation = true;
tcellbutton.Controls.Add(b);
tr.Cells.Add(tcellbutton);
table.Rows.Add(tr);
panel1.Controls.Add(table);

void b_Click(object sender, EventArgs e)
{
    string studentnumber = (sender as Button).ID.ToString().Substring(3, (sender as Button).ID.ToString().Length - 3);
    TextBox t = panel1.FindControl("txt" + studentNumber) as TextBox;
}

Is there another way to create and attach buttons in Sharepoint?

Fix your formatting and put in a full code snippet (what method or event are you adding the controls in, for example - this is almost certainly the problem and you've left it out) and it might get you a little more help. — Ryan
– Ryan, Commented Oct 20, 2010 at 8:03
Hi Ryan, My problem here is basically I can not attach events to controls during runtime, It has to be during the Page Initialization, I can override and run the same code without any error but my question is if it is available in the runtime as well.. — Kubi
– Kubi, Commented Oct 20, 2010 at 8:39

abatishchev · Accepted Answer · 2010-10-20 10:19:48Z

2

Ok here is how I solved it, Thanks for all replies, I was looking for a way to attach an event to a button that is created dynamically during runtime (after initialization). Hope It works for others as well.

<script type="text/javascript">
    function ButtonClick(buttonId) {
        alert("Button " + buttonId + " clicked from javascript");
    }
</script> 

protected void Button_Click(object sender, EventArgs e)
{
    ClientScript.RegisterClientScriptBlock(this.GetType(), ((Button)sender).ID, "<script>alert('Button_Click');</script>");
    Response.Write(DateTime.Now.ToString() + ": " + ((Button)sender).ID + " was clicked");
}    

private Button GetButton(string id, string name)
{
    Button b = new Button();
    b.Text = name;
    b.ID = id;
    b.Click += new EventHandler(Button_Click);
    b.OnClientClick = "ButtonClick('" + b.ClientID + "')";
    return b;
}

edited Oct 20, 2010 at 10:19

abatishchev

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answered Oct 20, 2010 at 10:14

Kubi

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1 Comment

abatishchev Over a year ago

Don't forget to accept your own answer as correct (by pressing on a tick)

abatishchev · Accepted Answer · 2010-10-20 10:18:25Z

1

You should add your code in PreInit event, code below work good:

protected override void OnPreInit(EventArgs e)
{
    base.OnPreInit(e);
    Button bb = new Button();
    bb.Click += new EventHandler(bb_Click);
    bb.CausesValidation = true;
    bb.ID = "button1";
    Panel1.Controls.Add(bb);
}

private void bb_Click(object sender, EventArgs e)
{
    Response.Write("any thing here");
}

edited Oct 20, 2010 at 10:18

abatishchev

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answered Oct 19, 2010 at 9:11

Tarek El-Mallah

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4 Comments

Kubi Over a year ago

is it possible to call OnPreInit() in another Event ?

Ryan Over a year ago

You don't call OnPreInit - the web part infrastructure calls it on your behalf. nishantrana.wordpress.com/2009/02/14/…

Tarek El-Mallah Over a year ago

you just override OnPreInit, not call it.

Tarek El-Mallah Over a year ago

@Kubi I think you can't, try below solution of @Kubi

psubsee2003 · Accepted Answer · 2012-10-28 00:31:39Z

1

You are creating dynamic controls. Your code should execute in each PageLoad event. Remove IsPostBack for the part of code where you are creating the buttons is my advice.

If you don't do this, you will create the controls, but each time when PageLoad event occurs, your control will be deleted and the application will not follow your events. With other words you should always recreate the controls.

edited Oct 28, 2012 at 0:31

psubsee2003

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answered Jan 31, 2012 at 8:01

Radu Cosoveanu

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